1. Field of the Invention
The invention relates generally to electro-optical connectors. More particularly, the invention relates to new interconnect structures, and techniques for fabricating these structures, which channel light from a plurality of light emitting locations to a plurality of light detecting locations, using one of several different energy transfer media for purposes of electronic data communication. The alternate embodiments of the energy transfer media have differing alignment criteria for the light sources, detectors and the media itself, provide differing amounts of immunity to crosstalk, immunity to transmissions losses, etc., which allow particular media to be chosen based on application requirements.
2. Description of the Related Art
Increasing input-output count requirements have produced demands for connectors which require less area, offer reduced Electromagnetic Interference (EMI), are reliable and inexpensive. Different applications for the connectors also require supporting a variety of differing data rates, acceptable transmission loss criteria, levels of immunity to crosstalk, etc.
It is becoming increasingly difficult to meet these demands using conventional pin-in-hole connectors, where contact to adjacent contact spacings of less than 50 to 100 mils are hard to achieve.
Furthermore, electromechanical connectors require a high contact force in order to break through the metal oxide on the connector surface. Where high-density interconnections are needed this contact force requirement becomes a serious problem whose solution requires the application of pressure to each pin of the connector through mechanical or hydraulic devices which transmit the requisite force to each of the connector pins. This greatly increases the size, complexity and cost of the interconnect.
In addition to these physical constraints, the electrical characteristics of pin-in-hole connectors produce undesirable side effects. In particular, self-inductance and parasitic capacitances between the various pins in the connector are problems. The inductances associated with these connectors broadcast electromagnetic waves, thus causing EMI which is known to vary in magnitude as Ldi/dt, where L is the inductance of the connector and di/dt is the rate of change of the current through the connector over time.
It has long been known that EMI associated with the inductance of these connectors will grow much worse as the clock rates of very large scale integrated (VLSI) devices (hence di/dt) increase. As it is already difficult to meet FCC standards with current levels of EMI, this problem will become quite serious as added burdens are placed on conventional pin-in-hole technology.
Still further, the aforementioned capacitances, which exist between different pins on a typical connector, cause electrical crosstalk, i.e., the mixing of the signals on one pin of the connector with the signals on other pins of the connector. This capacitively coupled crosstalk is exacerbated as clock rates increase, which is another key concern for future VLSI designs.
Electro-optical solutions to these problems would offer considerably greater contact density at relatively low cost. Low EMI is an inherent characteristic of optical coupling which will reduce noise. Contact force requirements associated with electromechanical connectors could be eliminated. Various levels of crosstalk immunity could be achieved as a function of the particular energy transfer media used to couple to the light emitting and light detecting locations, etc.
Accordingly, it would be desirable to be able to use electro-optical connectors employing energy transfer media (e.g., light imaging elements) most suited to the alignment constraints, density, crosstalk immunity, speed, transmission efficiency, etc. of a given application.
Furthermore, it would be desirable to be able to employ electro-optical connectors using the aforementioned energy transfer media for both direct optical connections, i.e., over short distances of, for example, on the order of approximately 1 cm; and for remote optical connections over relatively long distances, for example, several meters or more.
Still further, it would be desirable to be able to construct and utilize flexible fiber bundles for carrying optical signals betwen remote locations, where the individual fibers of a bundle can be easily aligned and attached to whatever light imaging element is used in the electro-optical connector.